Liquid-crystalline elastomers (LCEs) are great candidates for smart artificial materials. On page 2319, D. S. Wiersma, C. Parmeggiani, and co-workers use direct laser writing to fabricate 3D LCE structures with sub-micrometer resolution and maintaining the designed molecular orientation. This technique opens up the road towards 3D microphotonics in elastomers, and lays the basis for creating 3D, micrometer-size robotic structures, which can be controlled by light.

Active, paper-based, microfluidic chips driven by electrowetting are fabricated and demonstrated for reagent transport and mixing by K. Shin, O.-S. Kwon, and co-workers on page 2335. The key advantage in fabricating the paper-based microfluidic chips is that electrode patterns can be designed and printed on paper quickly, finely, and precisely without complicated wet-lab processes. The cover image showes that the inkjet-printed patterned electrodes can be employed to actuate liquid drops on paper, not only photo paper, but virtually any paper, such as recycled magazine paper.

On Page 2359, X. Yang, G. Lu, and co-workers introduce a method to improve the thermoelectric properties of polymers, upon constructing an interpenetrating network of a thermoelectric polymer within an insulating polymer matrix. The local one-dimensional charge transport along the conductive network simultaneously leads to lower thermal conductivity and higher electrical conductivity without sacrificing the Seebeck coefficient. This work promotes a conjugated-/insulating-polymer blend towards its application in all-polymer artificial skin and temperature sensors.

Nanocarbon hybrids are a class of material in which a nanocarbon (e.g., carbon nanotube, graphene) is in close contact with a second active component. Hybrids prepared by a range of synthesis strategies excel in a variety of energy and environmental applications such as catalysis, energy storage, energy conversion and sensors.

Chiral nematic structures with different helical pitch from layer to layer are embedded into phenol-formaldehyde bilayer resin composite films using cellulose nanocrystals (CNCs) as templates. Selective removal of CNCs results in mesoporous resins with different pore size and helical pitch between the layers. Consequently, these materials exhibit photonic properties by selectively reflecting lights of two different wavelengths and concomitant actuation properties.

Artificial ion channels are introduced into a photosystem II photoelectrical conversion system to mimic the photocurrent regulating of the natural PSII energy system on the thylakoid membrane. In the composite system, PSII complexes act as pumps to convert light into currents and artificial ion channels act as valves to regulate light-induced ionic currents.

Active, paper-based, microfluidic chips driven by electrowetting are fabricated and demonstrated for reagent transport and mixing. Instead of using the passive capillary force on the pulp to actuate a flow of a liquid, a group of digital drops are transported along programmed trajectories above the electrodes printed on low-cost paper, which should allow point-of-care production and diagnostic activities in the future.

The photocarrier transport properties in two leading molecular bulk-heterojunction systems, p-DTS(PTTh2)2:PC71BM and p-DTS(FBTTh2)2:PC71BM, are studied using transient photoconductivity measurements. We find that in these systems shallow trap states are distributed at relatively narrow energy range, giving rise to time-independent carrier mobility in the nanosecond time regime that evidently contributes to the high performance of molecular-based OPV devices.

Pressure-induced superconductivity is oberserved in Ca10(Pt3As8)(Fe2As2)5 by in situ high-pressure resistance and magnetic susceptibility measurements. Scaling of the pressure-induced and doping-induced superconductivity shows that the electronic phase diagrams of the pressurized and chemically doped 10–3–8 compound are similar in the moderate pressure and doping range but are disparate at higher pressure and heavy doping.

Giant electromagnetic field enhancement in specifically designed hot-spots plays a key role in chemical sensing via plasmon-assisted Raman spectroscopy. On page 2353, A. Toma and co-workers present novel 3D nanostar dimer structures that enable field confinement in highly localized regions, which are decoupled from the substrate surface by their elevated architecture. These nanostar dimers can be exploited for single/few molecules detection.

Plasmonic nanostar-dimers, decoupled from the substrate, have been fabricated by combining electron-beam lithography and reactive-ion etching techniques. The 3D architecture, the sharp tips of the nanostars and the sub-10 nm gap size promote the formation of giant electric-field in highly localized hot-spots. The single/few molecule detection capability of the 3D nanostar-dimers has been demonstrated by Surface-Enhanced Raman Scattering.

Thermoelectric properties of conjugated polymers are found to improve upon homogeneously distributing conjugated polymer into an insulating supporting matrix. The local one-dimensional charge transport along the interpenetration conductive network simultaneously leads to lower thermal conductivity, higher electrical conductivity without sacrifice of Seebeck coefficient, and thus a higher figure of merit ZT, as compared with neat conjugated polymer.

Auxetic behavior in low porosity metallic structures is demonstrated via a simple system of orthogonal elliptical voids. In this minimal 2D system, the Poisson's ratio can be effectively controlled by changing the aspect ratio of the voids. In this way, large negative values of Poisson's ratio can be achieved, indicating an effective strategy for designing auxetic structures with desired porosity.

Using cell-surface modification and biotin–streptavidin interactions, immune cells and target tumor cells are made to form multicellular assemblies. A polythiophene derivative can undergo cellular uptake, allowing the sensitization of oxygen under light irradiation. The subsequent generation of reactive oxygen species (ROS) regulates cell–cell communication in time and space.

Fluoroalkylsilane (FTS) acts as an efficient p-type dopant for organic semiconductors. FTS-doped films of the semicrystalline PBTTT polymer exhibit relatively high conductivities. We demonstrate that highly doped PBTTT films exhibit a metallic nature with clear Pauli paramagnetism as observed microscopically using electron spin resonance spectroscopy. The metallic state is realized within crystalline grains, as confirmed from the anisotropy of the ESR signal.

A novel device is designed for on-chip selective trap and two-dimensional remote manipulation of single and multiple fluid-borne magnetic particles using field controlled magnetic domain walls in circular nanostructures. The combination of different ring-shaped nanostructures and field sequences allows for remote manipulation of magnetic particles with high-precision along any arbitrary pathway on a chip surface.

A novel class of nanoparticles is developed for the co-delivery of a short cell penetrating peptide and a chemotherapeutic drug to achieve enhanced cytotoxicity. Tunable cytotoxicity is achieved through non-toxic peptide-facilitated gating. The strategy relies on a one-step blending process from polymer building blocks to form monodisperse, PEGylated particles that are sensitive to cellular pH variations. By varying the amount of peptide loading, the chemotherapeutic effects can be enhanced by up to 30-fold.

A path-length bias of nucleated electrochemical growth in a 3D periodic nano­maze is found to cause facet formation of an intrinsically isotropic material in a porous self-assembled gyroid network. This is the first report of faceted electrochemical growth that is not based on the crystallographic order of the constituent building blocks, but rather reflects the symmetry of the template in which the material is synthesized.

Strongly coupled NiCo2O4-rGO hybrid nanosheets are syntheiszed through a cost-effective two-step strategy involving a facile polyol process and subsequent thermal annealing treatment in air. The hybrid nanosheets exhibit impressive electrocatalytic performance for the oxygen reduction reaction (ORR) with a current density and onset potential comparable to those of commercial Pt/C catalyts, while having perfect tolerance to methanol..

An optical nose chip is developed using surface functionalized mesoporous colloidal photonic crystal beads as elements. The prepared optical nose chip displays excellent discrimination among a very wide range of compounds, not only the simplex organic vapors from the different or same chemical family, but also the complex expiratory air from different people.

Quasi-quaternary nanocrystal superlattices are assembled by using exclusively core-shell particles as building blocks. The assemblies show an enhancement of energy-transfer from cadmium selenide-based core-shell quantum dots to gold-iron oxide core-shell nanocrystals compared to random mixtures of the same components.

A simple DNA-mediated solvothermal method has been developed for the construction of well-defined hollow UNPs that can be used for a new paradigm to realize NIR light-controlled non-invasive protein release. In vitro studies show that the UNPs are capable of the transportation of enzyme into living cells. Intracellular NIR triggers the release of enzymes with high spatial and temporal precision and the released enzyme also retains its biological activity.

A hierarchical nanoparticle strategy to simultaneously gain super Raman signal amplification, high uniformity, and reproducibility is presented. Using hollow Au-Ag alloy nanourchins, an ultrahigh sensitivity, e.g., down to 1 fM concentrations for DEHP molecule is obtained. A small standard deviation of <10% is achieved by simply dropping and evaporating sub-100 nm nanourchins onto a substrate.

Ideal 3D electrodes offer kinetics and mass transport advantages in electrochemical energy storage. The common features of ideal 3D electrodes are summarized and recent advances in both template-assisted and template-free synthesis, as well as the electrode performance, are reviewed.